Hydraulic load indicating device

ABSTRACT

A hydraulic device is interposed between the vehicle spring and a wheel support member of a motor vehicle suspension system. The device contains an expansible chamber that changes its volume in proportion to the vehicle loading. The chamber volume is sensed by an indicator that gives a reading to the vehicle operator of the load being carried by the vehicle.

United States Patent [1 1 Thorn et a1.

[54] HYDRAULIC LOAD INDICATING DEVICE [75] Inventors: John E. Thorn,Chigwell Row; Alan A. Selman, Southend-on-Sea, both of England [73]Assignee: Ford Motor Company, Dearborn,

Mich.

[22] Filed: June 25, 1970 [21] Appl. No.: 49,692

[30] Foreign Application Priority Data Aug. 26, 1969 Great Britain..42,425/69 [52] U.S. Cl. ..177/141, 177/137, 177/208, v 177/209 [51]Int. Cl. ..G0lg 19/10, GOlg 5/00 [58] Field of Search ..177/136-138,141, 177/208, 209; 73/141 A, 141 AB [56] References Cited UNITED STATESPATENTS 1,432,631 10/1922 Sonnlechner et al ..177/138 3,150,729 9/1964Mehki ..177/141 3,241,626 3/1966 Woodburn ..177/137 1,147,128 7/1915Troll 177/137 X 1,532,835 4/1925 Schlabach ..177/209 X 2,482,027 9/1949Poole ..177/136 X 111 3,724,571 [451 Apr. 3, 1973 1,227,503 5/1917 Troll..177/209 1,877,980 9/1932 Schafer... ..177/209 X 1,995,996 3/1935Moore.... ..177/208 X 2,109,460 3/1938 Brasher 177/208 UX 2,472,6896/1949 Adams et a1.... ..177/209 X 2,830,804 4/1958 Fisher ..177/2092,867,433 1/1959 Bergenheim et al. .177/208 UX 3,147,616 9/1964 Rome..177/208 X FOREIGN PATENTS OR APPLICATIONS 1,353,831 1/1964 France..177/137 512,620 7/1952 Belgium ...177/209 736,658 6/1966 Canada177/141 574,901 4/1924 France 177/141 1,535,073 6/1968 France 177/209509,640 7/1939 Great Britain ....177/l41 1,081,977 9/1967 Great Britain..177/141 Primary ExaminerRichard B. Wilkinson AssistantExaminer-Stanley J. Witkowski ArtorneyJohn R. Faulkner and Clifford L.Sadler [57] ABSTRACT A hydraulic deviceis interposed between the vehiclespring and a wheel support member of a motor vehicle suspension system.The device contains an expansible chamber that changes its volume inproportion to the vehicle loading. The chamber volume is sensed by anindicator that gives a reading to the vehicle operator of the load beingcarried by the vehicle.

5 Claims, 3 Drawing Figures PATENTEUAPR 3 197a SHEET 1 OF 2 FlG.l

- INVENTORS (/OH/V A. THOR/V AKA/V ,4. SA-ZMA/V yJw 2111M ATTORNEYSBACKGROUND OF THE INVENTION This invention relates to devices forindicating or measuring the load of a motor vehicle or the load on aparticular wheel or axle of the vehicle.

In order to comply with regulations relating to the loading ofcommercial motor vehicles and in order to avoid overloading or unsafedistribution of loads, it is necessary to frequently measure the axleloading of such vehicles. The present method of weighing loaded vehiclesinvolves driving the vehicle onto a weighing device such as a permanentor portable scale. The scale gives the amount of load on each wheel oron each axle, depending upon how it is constructed.

This is clearly inconvenient and a system installed permanently in thevehicle to indicate the magnitude of the load on each axle would be ofconsiderable utility. A simple system of this kind might measure thestatic deflection of the suspension spring which varies with the loadcarried by the vehicle. Springs of the kind used in motor vehicles,however, are subject to hysteresis and permanent set. The staticdeflection of the vehicle spring, therefore, may not bear an accuraterelationship to axle loading.

In view of the state of the art, it is one of the principal objects ofthe present invention to provide an efficient simple and compactmeasuring device having load sensors permanently situated between thevehicle springs and the axle for the purpose of measuring vehicleloading.

BRIEF SUMMARY OF THE PREFERRED EMBODIMENT In one preferred embodiment ofthe present invention, a motor vehicle has a leaf spring suspension witha pair of leaf spring assemblies secured to the outer ends of thevehicle axle. A pair of hydraulic sensing devices is interposed betweeneach spring and the axle. The sensors each contain an expansible chamberwith one wall that is constructed to flex in response to changes invehicle loading.

The several sensors are interconnected to an indicator device situatedon the instrument panel in the cab of the vehicle. The indicator has afloating piston that is constructed to be displaced in response tochanges in the volume of the chambers in the load sensors.

The flexing of the walls of the sensor chambers, in response to anincrease or decrease in vehicle loading, changes the volume of thechambers and this volume change is hydraulically transmitted to theindicator device. The piston in the indicator moves in response to thefluid displaced. The indicator devices includes a scale and a pointer,which is connected to the piston, in order to obtain a direct readingthat is proportional to the load on the vehicle axle.

GENERAL DESCRIPTION OF THE DRAWING The many objects and advantages ofthe present device will become apparent from the following descriptionand the accompanying drawings, in which:

FIG. 2 shows the load sensing device of FIG. 1, partially in sectionalview, and assembled with the vehicle axle and spring. An indicatormechanism is connected to the load sensing device.

FIG. 3 is a schematic representation of an automatic system forcontrolling the hydraulic valves of FIGS. 1 and 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to thedrawings, wherein the presently preferred embodiment of this inventionis shown, a truck or other commercial vehicle has an unsprung mass whichincludes a vehicle body (not shown) supported by means of leaf springs12. A pair of load sensing devices are interposed between each leafspring 12 and the axle 10 as shown in FIG. 2.

Load sensing devices 14 and 16 are arranged in pairs and secured toeither side of the axle 10 by U-bolts 18. As illustrated in FIG. 1, theload sensors 14 and 16 are situated near one outer end of the axle 10.Similarly, a pair of load sensors 20 and 22 are secured near the otherend of the axle 10. As at the first endof the axle, U-bolts (not shown)secure the sensors 20 and 22 in position with respect to the other endof the axle l0 and a leaf spring (not shown).

Referring to FIG. 2, the sensor 14 includesa rigid upper housing member24 having a generally concave shape. A flexible member 26 closes theconcavity of the member 24 whereby an internal chamber 28 is definedwith the member 26 forming one flexible wall of the chamber 28. Apassage 31 in the housing 24 is connected to the chamber 28. Theflexible member 26 has a diaphragm portion 30 and a centrally situatedenlarged boss 32. The boss 32 limits the deflection of the flexiblemember 26 by its engagement with the inner wall surface of the cavity inthe member 24. The boss 32 also extends from the opposite side of theflexible member 26 and engages a plate 34 resting on the axle 10.

The lower load sensor 16 is similarly constructed and includes a concaverigid member 36 and a flexible member 38 which combine to define achamber 40. The central enlarged boss 42 of the flexible member 38engages the plate 44 positioned adjacent the lower side of the axle 10.

Two metal spacers 46 and 48 are interposed between the flexible members26 and 38 and separate the load sensors 14 and 16. The entire assemblycomprising the load sensors 14 and 16, spacers 46 and 48, and axle 10are secured or clamped to the leaf spring assembly 12 by means ofU-bolts 18.

The sensors 20 and 22 are similarly constructed and arranged.

Referring to FIG. 1, it will be seen that hydraulic line 52interconnects the chamber 28 of load sensor 14 and the chamber of loadsensor 20. Similarly, hydraulic line 54 provides communication betweenthe hydraulic chamber 40 of sensor 16 and the corresponding chamber ofsensor 22. Hydraulic line 52 is connected through valve 58 to line 56which, in turn, is connected to a load indicator device 60. Hydraulicline 54 interconnecting the load sensors 16 and 22 is connected througha hydraulic line 62 to the indicating device 60. A cutoff valve 64 isinterposed in line 62.

Indicating device 60 includes a cylinder 66 having a piston 68 slidabletherein. An indicator arm 70 is pivotally supported at 72 and has oneend 74 that engages the piston 60. The opposite end of indicator arm 60has a pointer portion that cooperates with a scale 76 that is calibratedto indicate the static loading on the axle 10.

OPERATION The several load sensors 14, 16, 20 and 22 as well as theseveral hydraulic lines 52, 54, 56, 62 and cylinder 66 are filled withhydraulic fluid. It will be seen that downward movement of the spring 12relative to the axle caused by an increase in the static load on thevehicle will result in the reduction in the volume of chamber 28 ofsensor 14. A similar decrease in the volume of the chamber in sensorwill also take place. Correspondingly, the volume of the chamber 40 ofsensor 16 and the volume of the chamber within sensor 22 will increase.These several volume changes will occur as a result of the. flexibilityof the members 26 and 38.

In order to accommodate the changes in volume, it is assumed that thevalves 58 and 64 are open. Referring to FIG. 2, when the volume ofchamber 28 is decreased fluid will flow through the hydraulic line 52,valve 58 and line 56 to the cylinder 66. This will cause the piston 68to move to the right. A corresponding volume of fluid will flow throughthe hydraulic lines 62 and 54 to the chamber 40 of the load sensor 16 asthe piston 68 is displaced. Movement of the piston, in turn, will causethe indicator arm 70 to be displaced in a counterclockwise direction.The end of thearm 70, in cooperation with the scale 76, will indicate anincrease in vehicle static loading. 7

The reading of indicator device 60 is to be taken when the vehicle isstationary and the valves 58 and 64 are open. Once the load has beenindicated and the vehicle is to be moved, valves 58 and 64 are closed.This has the effect of creating a solid hydraulic lock which locates theaxle 10 in its deflected position relative to the leaf spring 12 of thesuspension system. In this condition, indicator arm 22 will continue toregister the applied static load while hydraulic pressure within thechambers 28 and 40 resists bump loads applied to the axle during themotion of the vehicle.

The valves 58 and 64 may be automatically controlled so that they areautomatically opened when the vehicle is parked and automatically closedas soon as the vehicle moves or is about to move. For example, thevalves 58 and 64 may be made responsive to the operation of the parkingbrake pedal of the vehicle.

In FIG. 3, a parking brake lever 80 is pivotally supported to actuate aparking brake cable 82. Valves 58 and 64 are controlled by solenoids 84and 86. The valves 58 and 64, under the control of solenoids 84 and 86,are constructed to be normally closed. The solenoids 84 and 86 are inparallel circuitry with an electrical power source such as the vehiclebattery 88 and a normally opened switch 90. The switch 90 is constructedto be closed upon application of the parking brake pedal 80. When theparking brake pedal 80 is depressed, the switch 90 is closed causing thesolenoids 84 and 86 to be activated which, in turn, opens the valves 58and 64.

With the system of FIG. 3, the load measuring device of FIG. Iautomatically functions when the vehicle has its parking brakes applied.When the parking brake is released and the vehicle is about to be moved,the valves 58 and 64 are closed.

With the control system of FIG. 3, the hydraulic sensors 14, 16, 20 and22 will be automatically locked so that no deflection will occur betweenthe ring 12 and the axle 10 when the vehicle is moving or is about tomove.

It is also to be appreciated that the control switch could be connectedto the speedometer and made vehicle speed responsive whereby the valves58 and 64 would automatically close when the vehicle is in motion. Analternate construction would connect the control switch 90 to theignition switch of the vehicle whereby whenever the ignition switch isin the run" position, the valves 58 and 64 would be closed.

The foregoing description presents the presently preferred embodiment ofthis invention. Modifications and alterations may occur to those skilledin the art which will come within the scope and spirit of the followingclaims:

We claim:

1.'A load indicating mechanism for a motor vehicle having sprung andunsprung components including an axle, said axle being constructed torotatably support a road wheel at each of its outer ends, a vehicle bodysupport spring positioned adjacent each end of said axle and connectedto said sprung components, each end of said axle having a pair ofhydraulic load sensing devices situated one aboveand one beneath saidaxle, separate mounting meanssecuring each of said springs and theadjacent pair of load sensing devices to said axle, each of saidhydraulic load sensing devices having an expansible chamber constructedto change in volume in response to the amount of load on said sprungcomponents, the expansible chambers of the upper load sensing devicesbeing interconnected, the expansible chambers of the lower load sensingdevices being interconnected, said chambers being connected to ahydraulically operated load indicating device, said load indicatingdevice having means for displaying load information in response to theflow of fluid into and out of said chambers.

2. A load indicating mechanism for a motor vehicle according to claim 1and including:

valve means constructed to prevent the flow of fluid into and out ofsaid chambers. 3. A load indicating mechanism for a motor vehicleaccording to claim 1 and including:

valve means constructed to prevent the flow of fluid into and out ofsaid chambers, automatic valve actuating means connected to said valvemeans and constructed to normally maintain said valve means in a closedcondition. 4. A load indicating mechanism for a motor vehicle havingsprung and unsprung components including an axle, said axle beingconstructed to rotatably support a road wheel at each of its outer ends,a vehicle body support spring positioned adjacent each end of said axleand connected to said sprung components, each end of said axle having apair of hydraulic load'sensing devices situated one above and onebeneath said axle, separate mounting means securing each of said springsand the adjacent pair of load sensing devices to said axle, each of saidhydraulic load sensing devices having an expansible chamber constructedto change in volume in response to the amount of load on said sprungcomponents, the expansible chambers of the upper load sensing devicesbeing interconnected, the expansible chambers of the lower load sensingdevices being interconnected, said chambers being connected to ahydraulically operated load indicating device, said load indicatingdevice having means for displaying load information in response to theflow of fluid into and out of said chambers, valve means constructed toprevent the 5. A load indicating mechanism for a motor vehicle accordingto claim 4 and including:

said vehicle having brake applying means, said valve actuating meansbeing constructed to be responsive to the actuation of said brakeapplying means to open said valve means.

1. A load indicating mechanism for a motor vehicle having sprung andunsprung components including an axle, said axle being constructed torotatably support a road wheel at each of its outer ends, a vehicle bodysupport spring positioned adjacent each end of said axle and connectedto said sprung components, each end of said axle having a pair ofhydraulic load sensing devices situated one above and one beneath saidaxle, separate mounting means securing each of said springs and theadjacent pair of load sensing devices to said axle, each of saidhydraulic load sensing devices having an expansible chamber constructedto change in volume in response to the amount of load on said sprungcomponents, the expansible chambers of the upper load sensing devicesbeing interconnected, the expansible chambers of the lower load sensingdevices being interconnected, said chambers being connected to ahydraulically operated load indicating device, said load indicatingdevice having means for displaying load information in response to theflow of fluid into and out of said chambers.
 2. A load indicatingmechanism for a motor vehicle according to claim 1 and including: valvemeans constructed to prevent the flow of fluid into and out of saidchambers.
 3. A load indicating mechanism for a motor vehicle accordingto claim 1 and including: valve means constructed to prevent the flow offluid into and out of said chambers, automatic valve actuating meansconnected to said valve means and constructed to normally maintain saidvalve means in a closed condition.
 4. A load indicating mechanism for amotor vehicle having sprung and unsprung components including an axle,said axle being constructed to rotatably support a road wheel at each ofits outer ends, a vehicle body support spring positioned adjacent eachend of said axle and connected to said sprung components, each end ofsaid axle having a pair of hydraulic load sensing devices situated oneabove and one beneath said axle, separate mounting means securing eachof said springs and the adjacent pair of load sensing devices to saidaxle, each of said hydraulic load sensing devices having an expansiblechamber constructed to change in volume in response to the amount ofload on said sprung components, the expansible chambers of the upperload sensing devices being interconnected, the expansible chambers ofthe lower load sensing devices being interconnected, said chambers beingconnected to a hydraulically operated load indicating device, said loadindicating device having means for displaying load information inresponse to the flow of fluid into and out of said chambers, valve meansconstructed to prevent the flow of fluid into and out of said chambers,automatic valve actuating means connected to said valve means andconstructed to normally maintain said valve means in a closed condition,said valve actuating means being responsive to a pre-establishedoperating condition of said vehicle to open said valve means.
 5. A loadindicating mechanism for a motor vehicle according to claim 4 andincluding: said vehicle having brake applying means, said valveactuating means being constructed to be responsive to the actuation ofsaid brake applying means to open said valve means.